Making a re-useable function of JSON URL fetching function in SWIFT 2.0 - ios

Question

I am stuck in a problem. I think it is all due to my weak basics. I am sure someone can help me easily and put me in the right direction.
I have different segues and all get the data from JSON via remote URL.
So in-short all segues need to open URL and parse JSON and make them into an ARRAY
I have made the first segue and it is working fine.
Now i plan to use the functions where it download JSON and turns it into ARRAY as a common function
I read in another page on stackoverflow that I can declare all common functions outside the class in ViewController
I hope everyone is with me this far.
now in ViewController i declare a function
getDataFromJson(url: String)
This function code looks like following
func getJsonFromURL(url: String)
{
// some class specific tasks
// call the common function with URL
// get an array
let arrJSON = getJsonArrFromURL(url)
for element in arrJSON
{
// assign each element in json to ur table
print("Element: \(element)")
}
// some class specific tasks
}
and this will call the common function declared outside the score of class
getArrFromJson(url: String) -> NSArray
This common function is just very generic.
Take a URL, call it, open it, parse its data into ARRAY and return it back.
The problem i am stuck is where to put the return
It returns empty array as the task is not finished and i am clueless
func getJsonArrFromURL(var url: String) -> NSArray
{
var parseJSON : NSArray?
if ( url == "" )
{
url = self.baseURLHomepage
}
print("Opening a JSON URL \(url)")
let myUrl = NSURL(string: url);
let request = NSMutableURLRequest(URL:myUrl!);
request.HTTPMethod = "GET";
let postString = "";
request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding);
let task = NSURLSession.sharedSession().dataTaskWithRequest(request)
{
data, response, error in
if ( error != nil )
{
print("Error open JSON url \n\(error)")
return
}
do
{
parseJSON = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers) as? NSArray
}
catch
{
self.showAlert("Error", msg: "Error occurred while trying to process the product information data")
print("Error occured in JSON = \(error)")
}
}
task.resume()
return parseJSON!
}

Answer 1

You can probably add a method like below in any of your class
func post(url: String, info: String, completionHandler: (NSString?, NSError?) -> ()) -> NSURLSessionTask {
let URL = NSURL(string: url)!
let request = NSMutableURLRequest(URL:URL)
request.HTTPMethod = "GET"
let bodyData = info
request.HTTPBody = bodyData.dataUsingEncoding(NSUTF8StringEncoding);
let task = NSURLSession.sharedSession().dataTaskWithRequest(request) { data, response, error in
dispatch_async(dispatch_get_main_queue()) {
guard data != nil else {
print("response String is nil")
completionHandler(nil, error)
return
}
if let dataNew = data {
completionHandler(NSString(data: (NSData(base64EncodedData: dataNew, options: NSDataBase64DecodingOptions([])))!, encoding: NSASCIIStringEncoding), nil)
}
}
}
task.resume()
return task
}
and access it anywhere like
let url = "your URL String"
let info = "The data you would like to pass"
yourClassName.post(url, info: info) { responseString, error in
guard responseString != nil else {
print("response String is nil")
print(error)
return
}
do {
if !(responseString as? String)!.isEmpty {
let json = try NSJSONSerialization.JSONObjectWithData((responseString as! String).data, options: NSJSONReadingOptions.init(rawValue: 0))
//process your json here
}
} catch {
print("Error\n \(error)")
return
}
}
Extend your string like follows
extension String {
var data:NSData! {
return dataUsingEncoding(NSUTF8StringEncoding)
}
}